Garden Q&A: At what strength should I use copper sulphate?

Whether you're a gardening beginner or expert, Irish Examiner columnist Peter Dowdall has the answer to your questions

Question

I found some copper sulphate in a shed. I would like to use it on my box pyramids. How much water should I use per ounce of copper sulphate?

Answer

Copper sulphate is an excellent fungicide offering a broad spectrum of control. It should not however be used too freely or at the wrong strength. 

I would only recommend using it once per year. It depends in what form and at what content of copper, as to how to dilute it. 

What you will buy in a garden centre is labelled copper mixture and is a white powder. 

Apply this at the rate of 35 grammes per 1.5 litres. If you source it as bluestone which has a different strength then the recommended mixture is 50 grammes of copper sulphate mixed with 60 grammes washing soda and five litres of water.

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